fsm_recode.cc

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/*
 *  yosys -- Yosys Open SYnthesis Suite
 *
 *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
 *  
 *  Permission to use, copy, modify, and/or distribute this software for any
 *  purpose with or without fee is hereby granted, provided that the above
 *  copyright notice and this permission notice appear in all copies.
 *  
 *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

#include "kernel/log.h"
#include "kernel/register.h"
#include "kernel/sigtools.h"
#include "kernel/consteval.h"
#include "kernel/celltypes.h"
#include "fsmdata.h"
#include <math.h>
#include <string.h>
#include <errno.h>

USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN

static void fm_set_fsm_print(RTLIL::Cell *cell, RTLIL::Module *module, FsmData &fsm_data, const char *prefix, FILE *f)
{
    std::string name = cell->parameters["\\NAME"].decode_string();

    fprintf(f, "set_fsm_state_vector {");
    for (int i = fsm_data.state_bits-1; i >= 0; i--)
        fprintf(f, " %s_reg[%d]", name[0] == '\\' ?  name.substr(1).c_str() : name.c_str(), i);
    fprintf(f, " } -name {%s_%s} {%s:/WORK/%s}\n", prefix, RTLIL::unescape_id(name).c_str(),
            prefix, RTLIL::unescape_id(module->name).c_str());

    fprintf(f, "set_fsm_encoding {");
    for (int i = 0; i < GetSize(fsm_data.state_table); i++) {
        fprintf(f, " s%d=2#", i);
        for (int j = GetSize(fsm_data.state_table[i].bits)-1; j >= 0; j--)
            fprintf(f, "%c", fsm_data.state_table[i].bits[j] == RTLIL::State::S1 ? '1' : '0');
    }
    fprintf(f, " } -name {%s_%s} {%s:/WORK/%s}\n",
            prefix, RTLIL::unescape_id(name).c_str(),
            prefix, RTLIL::unescape_id(module->name).c_str());
}

static void fsm_recode(RTLIL::Cell *cell, RTLIL::Module *module, FILE *fm_set_fsm_file, std::string default_encoding)
{
    std::string encoding = cell->attributes.count("\\fsm_encoding") ? cell->attributes.at("\\fsm_encoding").decode_string() : "auto";

    log("Recoding FSM `%s' from module `%s' using `%s' encoding:\n", cell->name.c_str(), module->name.c_str(), encoding.c_str());

    if (encoding != "none" && encoding != "one-hot" && encoding != "binary" && encoding != "auto") {
        log("  unknown encoding `%s': using auto instead.\n", encoding.c_str());
        encoding = "auto";
    }

    if (encoding == "none") {
        log("  nothing to do for encoding `none'.\n");
        return;
    }

    FsmData fsm_data;
    fsm_data.copy_from_cell(cell);

    if (fm_set_fsm_file != NULL)
        fm_set_fsm_print(cell, module, fsm_data, "r", fm_set_fsm_file);

    if (encoding == "auto") {
        if (!default_encoding.empty())
            encoding = default_encoding;
        else
            encoding = GetSize(fsm_data.state_table) < 32 ? "one-hot" : "binary";
        log("  mapping auto encoding to `%s` for this FSM.\n", encoding.c_str());
    }

    if (encoding == "one-hot") {
        fsm_data.state_bits = fsm_data.state_table.size();
    } else
    if (encoding == "binary") {
        int new_num_state_bits = ceil(log2(fsm_data.state_table.size()));
        if (fsm_data.state_bits == new_num_state_bits) {
            log("  existing encoding is already a packed binary encoding.\n");
            return;
        }
        fsm_data.state_bits = new_num_state_bits;
    } else
        log_error("FSM encoding `%s' is not supported!\n", encoding.c_str());
    
    int state_idx_counter = fsm_data.reset_state >= 0 ? 1 : 0;
    for (int i = 0; i < int(fsm_data.state_table.size()); i++)
    {
        int state_idx = fsm_data.reset_state == i ? 0 : state_idx_counter++;
        RTLIL::Const new_code;

        if (encoding == "one-hot") {
            new_code = RTLIL::Const(RTLIL::State::Sa, fsm_data.state_bits);
            new_code.bits[state_idx] = RTLIL::State::S1;
        } else
        if (encoding == "binary") {
            new_code = RTLIL::Const(state_idx, fsm_data.state_bits);
        } else
            log_abort();

        log("  %s -> %s\n", fsm_data.state_table[i].as_string().c_str(), new_code.as_string().c_str());
        fsm_data.state_table[i] = new_code;
    }

    if (fm_set_fsm_file != NULL)
        fm_set_fsm_print(cell, module, fsm_data, "i", fm_set_fsm_file);

    fsm_data.copy_to_cell(cell);
}

struct FsmRecodePass : public Pass {
    FsmRecodePass() : Pass("fsm_recode", "recoding finite state machines") { }
    virtual void help()
    {
        //   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
        log("\n");
        log("    fsm_recode [-encoding type] [-fm_set_fsm_file file] [selection]\n");
        log("\n");
        log("This pass reassign the state encodings for FSM cells. At the moment only\n");
        log("one-hot encoding and binary encoding is supported. The option -encoding\n");
        log("can be used to specify the encoding scheme used for FSMs without the\n");
        log("`fsm_encoding' attribute (or with the attribute set to `auto'.\n");
        log("\n");
        log("The option -fm_set_fsm_file can be used to generate a file containing the\n");
        log("mapping from old to new FSM encoding in form of Synopsys Formality set_fsm_*\n");
        log("commands.\n");
        log("\n");
    }
    virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
    {
        FILE *fm_set_fsm_file = NULL;
        std::string default_encoding;

        log_header("Executing FSM_RECODE pass (re-assigning FSM state encoding).\n");
        size_t argidx;
        for (argidx = 1; argidx < args.size(); argidx++) {
            std::string arg = args[argidx];
            if (arg == "-fm_set_fsm_file" && argidx+1 < args.size() && fm_set_fsm_file == NULL) {
                fm_set_fsm_file = fopen(args[++argidx].c_str(), "w");
                if (fm_set_fsm_file == NULL)
                    log_error("Can't open fm_set_fsm_file `%s' for writing: %s\n", args[argidx].c_str(), strerror(errno));
                continue;
            }
            if (arg == "-encoding" && argidx+1 < args.size() && fm_set_fsm_file == NULL) {
                default_encoding = args[++argidx];
                continue;
            }
            break;
        }
        extra_args(args, argidx, design);

        for (auto &mod_it : design->modules_)
            if (design->selected(mod_it.second))
                for (auto &cell_it : mod_it.second->cells_)
                    if (cell_it.second->type == "$fsm" && design->selected(mod_it.second, cell_it.second))
                        fsm_recode(cell_it.second, mod_it.second, fm_set_fsm_file, default_encoding);

        if (fm_set_fsm_file != NULL)
            fclose(fm_set_fsm_file);
    }
} FsmRecodePass;
 
PRIVATE_NAMESPACE_END